The detection of distinctive nucleic acid sequences in a biological sample is critical in many areas, including identifying microorganisms, diagnosing infectious diseases, detecting genetic abnormalities, identifying biomarker associated with various cancers, rating genetic susceptibility to selected diseases, and evaluating patient's response to medical treatments. Over the years, oligonucleotide-based DNA microarrays are becoming increasingly useful for the analysis of gene expression and single nucleotide polymorphisms. DNA microarrays may become a useful tool for large-scale parallel analyses of genome sequence and gene expression. Current applications of DNA microarrays include global analyses of transcriptional processes, evaluation of clinical course of tumors, and accelerated discovery of drug targets.
One way to fabricate DNA microarray is to spot DNA onto nylon membranes or glass slides by robots with pins or ink jet printers. This usually involves naturally available DNA molecules or fragments thereof. When the require DNA sequences are not naturally available, oligonucleotides may be synthesized de novo on the solid surface of the array in a controlled manner. Accordingly, new system and methods to allow controlled chemical synthesis on a solid surface are of interest in the biomedical and biopharmaceutical field.